Dora Anne Mills, Maine’s health officer, paused and seemed to draw a deep breath before answering the question, “Is mold a serious health threat in Maine?”

Some Mainers are certain it is. Brian and Lisa Priest, of Pembroke, for example. In a five-year dispute, they claim that improper design and construction of their $65,000 modular home promoted the growth of harmful mold leading to sinus and respiratory disease and forced them to move out. They are suing the dealer and two manufacturers.

Carolyn Smallidge says mold in her modular home in Pretty Marsh, on Mount Desert Island, has destroyed her life for the past four years. She says she was forced to move out and becomes ill when entering the house as briefly as 15 minutes. She, too, has retained a lawyer.

Other homeowners across the country complain that mold – often black stuff that grows uncontrollably out of light fixtures and on rugs and wallboard – has driven them out and forced them to pay many thousands of dollars to cleanup services. Lawsuits have been sprouting up, spurred largely by a $32 million jury award in a Texas mold-damage case. A federal appeals court later dismissed mental anguish and punitive damages but upheld a $4 million award for actual damages plus reduced legal fees.

Dr. Mills agrees that mold is a health threat in Maine, but added that the seriousness and extent are unknown. She noted that Maine has the highest asthma rate in the country for adults and probably the highest rate for children. She blamed in large part poor interior air quality – involving high exposure to second-hand smoke, radon, “and, we believe, mold.” Outdoor pollution, especially ozone, carried here on the jet stream from coal-burning plants in the Midwest, also contribute to the problem.

Many mold complaints in Maine go to Bob Stilwell, the radon and indoor air quality coordinator at the Maine Bureau of Health. He says: “The first thing to do about mold is: Calm Down! Mold is everywhere, all the time. If it’s growing in your house it’s because you have a water problem that’s gone on far too long.”

What to do about it, he says, is find the water problem, fix it, dry up the water, and clean up the mold, hiring help if necessary. He says soap and water works well on hard surfaces, but moldy carpeting, upholstery and sheet rock probably must be thrown out. Wear goggles, a respirator, gloves and washable clothing to do the job. And work fast. Mold can grow back in 48 hours if the moisture problem isn’t fixed.

Pay to test the mold? Mr. Stilwell says testing is rarely, if ever, necessary. There are no standards for how much mold is too much and no point in finding which type it is. He says not to be concerned about black mold. Except for people with mold allergies, the most common health effect of any mold is a stuffy head like hay fever, according to the U.S. Centers for Disease Control and Prevention.

Why the increasing concern? Partly, it’s environmentalists’ advice to save fuel by making houses airtight. And partly it’s doctors’ advice to raise the humidity. Proper construction, ventilation and possibly a dehumidifier can help prevent mold even in the tightest modular home.

It’s an old problem, going back to biblical times. The book of Leviticus refers to “plague” or mildew. “Watch the plague,” it says, “and if the plague spreads, the unclean item or property must be removed or destroyed.”

Good advise still.